1. Scope of Invention
This invention relates generally to lawn trimming devices, and more particularly to a grass trimming device connectable to the rotary output shaft of a lawn trimmer for removal of overgrown grass around a protective doughnut of an underground system sprinkler head.
2. Prior Art
Underground lawn sprinkler systems are well known and in wide use throughout the country. These systems include sprinkler heads mounted at or near grade level, some of which pop up when the sprinkler system is activated. However, when grass overgrows these sprinkler heads, sprinkling effectiveness is diminished or completely stifled.
Various lawn trimming devices, both manual and power activated, have been developed to trim the grass around the sprinkler heads. One such device is shown in U.S. Pat. No. 4,862,862 to Wait, et al. which discloses a rigid two-bladed cutting device connectable to the rotational output of a lawn trimmer also known as a "weed eater".
Another similarly activated device is shown in U.S. Pat. No. 4,357,752 invented by Goodwin which teaches a sprinkler head grass clipper having a generally cylindrical upright body for alignment over the sprinkler head to which is connected a plurality of outwardly extending cutting wires.
Richter, in U.S. Pat. No. 4,479,302 teaches a sprinkler head trimmer connectable to a conventional gasoline powered lawn edger which has an output shaft rotatable into an upright position to which is coupled a combination lawn edger and fixed blade sprinkler head trimmer.
Ford, in U.S. Pat. No. 3,555,680 teaches a manual sprinkler head trimmer connectable to a portable drill, this device teaching a series of three cylindrical concentric members each cooperatively functioning to trim the grass and dirt around a sprinkler head positioned below grade level.
In U.S. Pat. No. 3,747,213, a rotatably driven angular grass cutter for removal of grass and dirt around a sprinkler head is taught. This device is driven by an upright output shaft having fixed angular blades for cutting both soil and grass.
Various manual sprinkler head grass and lawn removers are shown in U.S. Pat. Nos. 4,260,026 to Deckert, in U.S. Pat. No. 4,022,283 to Morgan and in U.S. Pat. No. 3,960,218 to Atchley, et al. None of these above inventions are similar to that of the present invention except in a very general nature addressing removal of grass overgrown around a sprinkler head.
None of the prior art known to applicant teaches a sprinkler head trimming device having freely pivotable blades sized to fit around a protective doughnut placed around a sprinkler head and which trims overgrowth both around and within the circular central aperture of the doughnut in one easy step.